And a recent report by the Independent Monitoring Board found staff used force against detainees more than 300 times last year.

The Immigration Act 1971 allows anyone subject to immigration controls to be detained without any statutory limit.

Andrew Mitchell MP (Image: Isabel Infantes/PA Wire)

Many of those affected will have entered the country illegally or overstayed on a visa. Others are simply unable to prove their immigration status, and members of the Windrush generation have been wrongly detained.

Mr Mitchell said he did not see any evidence of detainees being mistreated at Brook House. But writing for website Conservative Home, he said: "Many people in immigration removal centres have never been charged with any crime, while some have previously been in prison following conviction for a criminal offence but have served their time.

"All are detained purely and simply because they are liable for removal. Some go on to be removed, but more than half are, at an arbitrary later date, released and able to remain in the UK temporarily or permanently.

"Recently, the most glaring abuse of this same immigration rule was the detention of English citizens who had come to the UK as children of the Windrush generation, an abuse of power which rightly generated a national outcry.

"The reality is that we remain the only country in Europe to detain people indefinitely for the purposes of immigration enforcement.

"So we need to ask ourselves whether the UK can reconcile the need to remove people without legal rights to remain in the country with a humane and just system of administration. In my opinion it can and it must."

Conservative MPs are set to put pressure on Prime Minister Theresa May to end indefinite detention. Dame Caroline Spelman, Cosnervative MP for Merdien, has previously called for a 28-day limit on detentions.